Geographic variation in surgical practice patterns and outcomes for resected nonmetastatic gastric cancer in Ontario

Background

Gastrectomy with negative resection margins and adequate lymph node dissection is the cornerstone of curative treatment for gastric cancer (gc). However, gastrectomy is a complex and invasive operation with significant morbidity and mortality. Little is known about surgical practice patterns or short- and long-term outcomes in early-stage gc in Canada.

Methods

We undertook a population-based retrospective cohort study of patients with gc diagnosed between 1 April 2005 and 31 March 2008. Chart review provided clinical and operative details such as disease stage, primary tumour location, surgical approach, operation, lymph nodes, and resection margins. Administrative data provided patient demographics, geography, and vital status. Variations in treatment and outcomes were compared for 14 local health integration networks. Descriptive statistics and log-rank tests were used to examine geographic variation.

Results

We identified 722 patients with nonmetastatic resected gc. We documented significant provincial variation in case mix, including primary tumour location, stage at diagnosis, and tumour grade. Short-term surgical outcomes varied across the province. The percentage of patients with 15 or fewer lymph nodes removed and examined varied from 41.8% to 73.8% (p = 0.02), and the rate of positive surgical margins ranged from 15.2% to 50.0% (p = 0.002). The 30-day surgical mortality rates did not vary statistically significantly across the province (p = 0.13); however, rates ranged from 0% to 16.7%. Overall 5-year survival was 44% and ranged from 31% to 55% across the province.

Conclusions

This cohort of patients with resected stages i-iii gc is the largest analyzed in Canada, providing important historical information about treatment outcomes. Understanding the causes of regional variation will support interventions aiming to improve gc operative outcomes in the cancer system.

Predictors of adjuvant treatment for pancreatic adenocarcinoma at the population level

BACKGROUND

In the present study, we aimed to describe, at the population level, patterns of adjuvant treatment use after curative-intent resection for pancreatic adenocarcinoma (pcc) and to identify independent predictors of adjuvant treatment use.

METHODS

In this observational cohort study, patients undergoing pcc resection in the province of Ontario (population 13 million) during 2005-2010 were identified using the provincial cancer registry and were linked to administrative databases that include all treatments received and outcomes experienced in the province. Patients were defined as having received chemotherapy (ctx), chemoradiation (crt), or observation (obs). Clinicopathologic factors associated with the use of ctx, crt, or obs were identified by chi-square test. Logistic regression analyses were used to identify independent predictors of adjuvant treatment versus obs, and ctx versus crt.

RESULTS

Of the 397 patients included, 75.3% received adjuvant treatment (27.2% crt, 48.1% ctx) and 24.7% received obs. Within a single-payer health care system with universal coverage of costs for ctx and crt, substantial variation by geographic region was observed. Although the likelihood of receiving adjuvant treatment increased from 2005 to 2010 (p = 0.002), multivariate analysis revealed widespread variation between the treating hospitals (p = 0.001), and even between high-volume hepatopancreatobiliary hospitals (p = 0.0006). Younger age, positive lymph nodes, and positive surgical resection margins predicted an increased likelihood of receiving adjuvant treatment. Among patients receiving adjuvant treatment, positive margins and a low comorbidity burden were associated with crt compared with ctx.

CONCLUSIONS

Interinstitutional medical practice variation contributes significantly to differential patterns in the rate of adjuvant treatment for pcc. Whether such variation is warranted or unwarranted requires further investigation.

Negative predictive value of preoperative computed tomography in determining pathologic local invasion, nodal disease, and abdominal metastases in gastric cancer

BACKGROUND

Before undergoing curative-intent resection of gastric adenocarcinoma (ga), most patients undergo abdominal computed tomography (ct) imaging to determine contraindications to resection (local invasion, distant metastases). However, the ability to detect contraindications is variable, and the literature is limited to single-institution studies. We sought to assess, on a population level, the clinical relevance of preoperative ct in evaluating the resectability of ga tumours in patients undergoing surgery.

METHODS

In a provincial cancer registry, 2414 patients with ga diagnosed during 2005-2008 at 116 institutions were identified, and a primary chart review of radiology, operative, and pathology reports was performed for all patients. Preoperative abdominal ct reports were compared with intraoperative findings and final pathology reports (reference standard) to determine the negative predictive value (npv) of ct in assessing local invasion, nodal involvement, and intra-abdominal metastases.

RESULTS

Among patients undergoing gastrectomy, the npv of ct imaging in detecting local invasion was 86.9% (n = 536). For nodal metastasis, the npv of ct was 43.3% (n = 450). Among patients undergoing surgical exploration, the npv of ct for intra-abdominal metastases was 52.3% (n = 407).

CONCLUSIONS

Preoperative abdominal ct imaging reported as negative is most accurate in determining local invasion and least accurate in nodal assessment. The poor npv of ct should be taken into account when selecting patients for staging laparoscopy.

Expression of ECM1 and MMP-2 in follicular thyroid lesions among Egyptians

BACKGROUND

Thyroid nodules require pre-surgical cytological assessment for possible risk of malignancy. Many techniques were introduced to enhance differential diagnosis and to avoid unnecessary diagnostic surgery.

OBJECTIVE

The study aims to investigate the potential use of ECM1 gene and MMP-2 protein as preoperative tumor markers in suspicious follicular thyroid lesions.

METHODS

The study included 40 Egyptian cases with solitary thyroid nodules. They underwent preoperative FNAB followed by thyroidectomy. MMP-2 protein and ECM1 gene were detected using immunostaining and conventional semi-quantitative RT-PCR techniques; respectively. The diagnostic accuracy of FNAB, gene and protein expression level cutoffs was calculated by using ROC.

RESULTS

Both MMP-2 protein and ECM1 gene expressions were significantly higher in malignant than benign group (P < 0.001). Both were significantly higher in higher tumor stages (PMMP-2= 0.002; PECM1 = 0.032) but only ECM1 significantly differed with tumor size (P < 0.006). The diagnostic performances of ECM1 expression scores was significantly better than that of FNAB (P = 0.049). A significant direct correlation was detected between ECM1 gene and MMP-2 protein expressions in cases of FVPC and of FC (P = 0.014).

CONCLUSIONS

MMP-2 protein and ECM1 gene are useful preoperative markers for defining malignancy in suspicious thyroid nodules.

The clinical anatomy of the triangle of Petit

INTRODUCTION

Hernias through the triangle of Petit (TP) are uncommon. The anatomy of the TP is known to be variable, yet quantitative data are scant.

MATERIALS AND METHODS

The triangle was observed in 80 adult cadavers and its dimensions and surface area were measured.

RESULTS

On the basis of surface area we classified the triangles into four types. Type I or small TP, with a surface area of <8 cm2, accounted for 43.7% of our specimens. Type II (26.2%) were intermediate in size, with a surface areas of 8-12 cm2. Type III (12.5%) were large triangles with surface areas >12 cm2. Finally, Type IV (17.5%) were not triangles. In these, the latissimus dorsi was covered by the external abdominal oblique muscle.

CONCLUSIONS

We hope these data will help prediction of which patients are at greater risk of herniation through the TP.

Identification of greater occipital nerve landmarks for the treatment of occipital neuralgia

Important structures involved in the pathogenesis of occipital headache include the aponeurotic attachments of the trapezius and semispinalis capitis muscles to the occipital bone. The greater occipital nerve (GON) can become entrapped as it passes through these aponeuroses, causing symptoms of occipital neuralgia. The aim of this study was to identify topographic landmarks for accurate identification of GON, which might facilitate its anaesthetic blockade. The course and distribution of GON and its relation to the aponeuroses of the trapezius and semispinalis capitis were examined in 100 formalin-fixed adult cadavers. In addition, the relative position of the nerve on a horizontal line between the external occipital protuberance and the mastoid process, as well as between the mastoid processes was measured. The greater occipital nerve was found bilaterally in all specimens. It was located at a mean distance of 3.8 cm (range 1.5-7.5 cm) lateral to a vertical line through the external occipital protuberance and the spinous processes of the cervical vertebrae 2-7. It was also located approximately 41% of the distance along the intermastoid line (medial to a mastoid process) and 22% of the distance between the external occipital protuberance and the mastoid process. The location of GON for anaesthesia or any other neurosurgical procedure has been established as one thumb's breadth lateral to the external occipital protuberance (2 cm laterally) and approximately at the base of the thumb nail (2 cm inferior). This is the first study proposing the use of landmarks in relation to anthropometric measurements. On the basis of these observations we propose a target zone for local anaesthetic injection that is based on easily identifiable landmarks and suggest that injection at this target point could be of benefit in the relief of occipital neuralgia.